A camera mounted on a vehicle monitors objects existing around the vehicle. There are demands for implementation of notification display suitable for a driver in accordance with a monitoring result. For this reason, when a plurality of objects including an object existing in a monitoring area are detected, a display device displays objects upon limiting a number of objects to be displayed to a number equal to or less than an upper limit of the number of objects to be displayed. On the other hand, when only objects existing outside the monitoring area are detected, the display device displays objects while display of the number of objects larger than the upper limit is allowed (see, for example, PTL 1).